Analysis of microRNA expression in synovial fluid and intra-articular tissues of osteonecrosis of the femoral head.

Objectives: Osteonecrosis of the femoral head (ONFH) is a progressive hip disorder often misdiagnosed owing to overlapping symptoms and radiographic findings. MicroRNAs (miRNAs) have emerged as potential diagnostic biomarkers; however, their role in ONFH remains unclear. This study analysed miRNA expression in synovial fluid and hip joint tissues of patients with ONFH to identify diagnostic markers.

Methods: Synovial fluid and hip joint tissues were collected from 24 patients with ONFH and 12 patients with osteoarthritis (OA) undergoing total hip arthroplasty. miRNA expression was assessed using microarray and validated using real-time polymerase chain reaction (PCR). Statistical analyses compared ONFH and OA groups and examined clinical factor correlations. Tissue-specific expression was evaluated in subchondral and cancellous bone, synovia, and labrum.

Results: Real-time PCR revealed significant upregulation of miR-210 (p < 0.01), miR-296, miR-659, and let-7c (p < 0.05) in ONFH synovial fluid compared to that of OA. Expression patterns were independent of clinical factors. miR-210 was also significantly upregulated in cancellous bone of the reparative zone in patients with ONFH (p < 0.05).

Conclusion: miR-210, miR-296, miR-659, and let-7c upregulations in ONFH synovial fluid independent of clinical factors indicates their potential as diagnostic markers. Localized increase in miR-210 in cancellous bone may indicate its role in ONFH pathophysiology.